Rotary engines have left a lasting impact on the automotive industry, particularly in Mazda sports cars. However, their history predates Mazda’s association with the rotary engine. In a recent episode of “Jay Leno’s Garage,” the early history of the rotary engine is explored, showcasing an NSU Spider from German automaker NSU, which played a significant role in introducing this unique engine design.
The rotary engine was originally invented by German engineer Felix Wankel and then licensed to various automakers. Unlike traditional piston engines, rotary engines use the energy from the combustion of fuel and oxygen to spin a rotor, instead of pushing pistons. The rotor, which has a triangular shape, is mounted in a roughly round housing. The corners of the triangle are designed to seal against the housing, creating open spaces on the sides that serve as the combustion chamber. In the case of the NSU Spider, a single spark plug ignites the fuel-air mixture, pushing against the sides of the rotor and causing it to spin.
One of the significant advantages of the rotary engine is its smooth operation and compact size. The NSU Spider’s engine is so small that it fits below the rear luggage compartment, allowing the convertible to have both a conventional trunk and a “frunk” to compensate for its small size. The air intake is cleverly located on the rear trunk lid, with the air directed down into the engine through a pipe in the trunk.
However, rotary engines also come with their fair share of disadvantages. They tend to consume more oil than conventional piston engines, and they possess an eagerness to rev that can be self-destructive. According to Jay Leno in the video, the NSU Spider can easily rev to 8,000 rpm, but this can wear out the rotor’s seals. In fact, the tachometer of the NSU Spider has a green zone that ends at around 5,500 rpm, encouraging more conservative driving behavior to preserve the longevity of the engine.
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In addition to these challenges, the NSU Spider was also relatively expensive for its time, costing around $3,500 in 1964, which was more than other small sports cars like the MGB. Despite its cost, the NSU Spider only offered 54 horsepower and sent power to the rear wheels through a 4-speed manual transmission. With a curb weight of approximately 1,500 pounds, driving the NSU Spider required patience and a willingness to work with its limitations.
After NSU introduced the rotary engine with the Spider, the company was acquired by the Volkswagen Group in the late 1960s and eventually merged into what would become Audi. However, rotary engines did not fade away. General Motors and Mercedes-Benz also experimented with rotary engines in the 1970s, and Mazda embraced and refined the technology, making it a staple in their lineup. Mazda’s rotary-powered RX-7 and RX-8 sports cars gained significant popularity, and in 1991, the rotary-powered Mazda 787B even became the first Japanese car to win the prestigious 24 Hours of Le Mans race. However, Mazda eventually discontinued rotary engine production in 2012.
But the story doesn’t end there. Earlier this year, Mazda announced the return of the rotary engine, albeit in a new form. The rotary engine will make a comeback as a range extender in the R-EV version of the MX-30 electric crossover. While this specific model won’t be available in the U.S., Mazda unveiled the electrified rotary concept called the Iconic SP at the 2023 Tokyo auto show, hinting at the continued existence of hopes for the return of the rotary sports car.
In conclusion, the rotary engine has a fascinating history that extends beyond its association with Mazda. From its beginnings with NSU, this unique engine design delivered smooth operation and a compact size. However, it also came with its own set of challenges, including high oil consumption and a proclivity to rev excessively. Despite its drawbacks, the rotary engine played a significant role in Mazda’s sports cars and even achieved a momentous victory at Le Mans. Now, with the announcement of its return in the form of a range extender, the rotary engine’s legacy continues to captivate automotive enthusiasts worldwide.
